UV index

noun

1.

a measure, on a scale of 0 to 11, of the intensity of ultraviolet radiation from the sun at the sun's highest point on a particular day in a particular place, a higher number indicating greater exposure.

(y'vē') A scale ranging from 0 to 10, used to estimate the risk for sunburn in midday sunlight, with 0 indicating no risk and 10 indicating maximal risk. The UV index is effectively a rough measure of the amount of harmful ultraviolet radiation in the sunlight reaching the Earth's surface at a given location, given the time of year and current atmospheric conditions, expressed in terms of the risks that are associated with exposure to that amount of radiation.